Conventionally, a variety of synthetic resins have been applied, according to their chemical and physical characteristics, to uses such as building materials, agricultural materials, miscellaneous goods, automobile parts, housings of electric appliances, coatings, and packaging materials.
Without resin stabilizers, most synthetic resins are deteriorated by heat or light. Therefore, an antioxidant such as a phenolic antioxidant, a phosphorus antioxidant, or a sulfur antioxidant; an ultraviolet absorber; or a hindered amine stabilizer has been added to the synthetic resins.
Conventionally, in order to stabilize a resin, a plurality of additives have also been added to the resin depending on the purpose of stabilization. Combination of such additives has been widely known to produce synergistic effects. For example, a combination of a phenolic antioxidant and a phosphorus antioxidant imparts heat resistance to the resin, and a combination of an ultraviolet absorber and a hindered amine stabilizer imparts weather resistance to the resin.
Among these additives, 2,2′-methylenebis(4-tert-octyl-6-benzotriazolyl)phenol is known to serve as an excellent ultraviolet absorber, as disclosed in Japanese Patent Application Laid-Open (kokai) No. 61-118373. Japanese Patent Application Laid-Open (kokai) Nos. 61-113649, 61-113667, 61-163954, 62-225554, 62-146951, 62-172058, 63-10653, etc. disclose uses of the phenol compound in a variety of resins.
However, 2,2′-methylenebis(4-tert-octyl-6-benzotriazolyl)phenol has poor compatibility with certain types of resin, such as polyolefin resin. When the compound is added to such a resin, the compound migrates to the surface of the resin products (i.e., exhibits blooming), thereby impairing the commercial value of the resin products. Therefore, limitations have been imposed on the type of resin to which the compound is added.
Thus, demand has arisen for improving the compatibility of 2,2′-methylenebis(4-tert-octyl-6-benzotriazolyl)phenol—an excellent ultraviolet absorber—to a resin, thereby enabling addition of the compound to a resin for which highly stabilizing effect is required.